Method of inserting materials in envelopes



Sept. 13, 1932. A. NOBLE 1,877,718

METHOD OF INSERTING MATERIALS IN ENVELOPES Filed Dec. 12, 1929 awventoz HUB/ff Y E. NOEL-E Patented Sept. 13, I932 METHOD OF INSERTING MATERIALS IN ENVELOPES Application filed December 12. 1929. Serial No. 413,480.

- This invention relates to a method of inserting within sealed envelopes, such aspositive column tubes, materials which are difficult to handle due to their explosive nature or due to the ease-with which they combine with moisture or the atmosphere or which may be difiicult or dangerous to handle for I cult to handle may and subjected to heat other reasons, or it may be merely desirable to handle the material in the manner to be described herein. Some examples of mate rlals which are diflicult to handle are the metals comprising the alkali or alkali earth groups of metals such as sodium, potassium and caesium.

An object of the invention is to provide method whereby any material and in particular a material which is dangerous or diffibe inserted safely and easily within an envelope which envelope may or may not be sealed.

e invention will be more apparent from the following description taken in connection with the drawing in which:

Figure 1 shows a positive column tube with a capsule placed within the electrode.

Figure 2 shows a partial section of the capsule.

In my co-pending application, Serial No. 413,481 filed on even date herewith, there has been described a method whereby materials and particularly such materials as the alkali and alkali earth metals of which sodium, potassium, and caesium are examples, are sealed in a casing forming a capsule which is readily handled. The materials to be utilized need not necessarily be diflicult to handle since the method described herein may also be used with any kind of material and it may be desirable only to apply them in the manner of this invention. The capsule consisting of a casing and the aterial sealed therein, is inserted within the envelope in which the material is subsequently to be liberated from its enclosing casing which causes the casing of the capsule to crack and open freeing the material enclosed therein which material may flow or spatter about within the envelope or become vaporized and become distributed theenvelope in its vapor form.

The capsule 1 shown in Figure 2 consists of a casing 2 of glass in which the material 3 to be liberated and preserved is sealed. Preferably the glass casing has thick walled ends 4 for a purpose to be subsequently discussed. Scratches 5 are made in the thick walled portions of the capsule as well as elsewhere. The entire capsule-need not be entirel filled with material and the space 6 may e evacuated if desirable in the manufacture of the capsule.

In order to break the casing to liberate the material therein, it is subjected to heat in any way. The heat breaks the casing which has been weakened by the scratches. Where the enclosing casing is of glass having portions of its walls of uneven thickness and'the capsule is heated, uneven strains are set up in the'casing which augmented by the weakening scratches assists in breaking the casing to liberate the enclosed material.

Other forms and types of capsules, it is apparent will also serve the purpose. Also a compound may be inserted within the casing which upon heating yields a gas and the material or metal desired. The gas liberated will assist in breaking the casing.

The heating of the capsule to open the enclosing casing is accomplished by heating the envelope adjacent to the capsule b a flame. A better way, however, is to place t e capsule in contact or close proximity with a high resistance metal, such as nickel, also within the envelope and this metal is then heated in any manner, the heat from the metal being transferred to the capsule and brea g it, to release the material sealed therein. One manner in which this metal may be heated is by placing a coil about the envelope so that it also surrounds the high resistance metal within the envelope and a high frequency electrical current passed through the coil which inductively heats the metal. The heat from the metal is transmitted to the capsule which cracks and opens liberating the material sealed therein. The capsule may also be heated by placing it in contact with a metallic wire heated by an electric current passing through the wire.

e process described broadly above is parbe depositedupon the ticularly applicable to the insertion of an alkali or alkali earth metal within the envelope of a positive column tube and adjacent to the electrodes. A capsule within inserted within. the envelope 8 and preferably within each of the electrodes 9 provided at either end of the tube. The tube is then evacuated through a connecting tube 10 con-. nected to an evacuating pump. The occluded gases are then driven off from the electrodes and the tube walls. The-driving 0d of the occluded gases is accomplished by subjecting the tube and the electrodes to heat in a manner known to the art and will not be described here other than to say that such heating may be carried out by passing through the tube a discharge" current of suflicient density to bring about the requisite degree of heating. This temperature to which the electrodes and tube is subjected by this heating is regulated so as to be not sufliciently high to crack and break the capsule and liberate the metal within the capsule. ,The evacuating of the tube and driving off of the occluded gases may require several beatings.

In order to cause breaking of the capsule casing, the casing is subjected to an even higher temperature than is necessary to drive off occluded gases. The high temperature may be obtained by passing between the electrodes of the tube a discharge current having a density sufliciently high to cause breaking of the capsule. The heavy current is passed through the tube for a short time only and the pump continues evacuation of the tube to remove the additional occluded gases thrown off by the tube and electrodes as a result of the increased temperature to which they have been subjected. The discharge current is supplied from the generator 12 through the transformer 14 and variable reactance 16.

If the electrodes of the positive column tube are of high resistance material, such'as nickel, these electrodes can more advantageously be heated to a temperature sufficient to break the capsule by surrounding the electrode within the envelope by an external coil carrying a high frequency current. This method of heating the electrodes is also applicable to electrodes of metals not having a high resistance, such as copper, but it requires a higher current and a longer time to raise thetemperature of the electrode sufliciently high to break the capsule so that for this reason the first method described is better suited. Upon the capsule casing breaking, the metal sealed therein spatters or flows about the electrode. If the electrode is a cylindrical shell the greater part of the metal will inner wall of the electrode. Where a more general distribution of -the potassium ormetal is desired, the 'elec-' [trode may lie-perforated or made of "metal screen. Upon breaking of the capsule casing the potassium spatters vover the entire electrode practically as well as upon the inner ope.

Preferably it is desirable to havethe capsule easing anchored within the electrode or envelope of the tube. Where the capsule is within the electrode and the electrode made of 'sheet material, the sheet may be snugly wrapped about the capsule when forming the electrode. When the capsule casing cracks and liberates the enclosed metal, the casing remains anchored and does not leave loose bits within the envelope. It is clear that the capsule need not be placed within the electrode but may be outside of the electrode so long as it is adjacent thereto. are provided for heating the capsule it is obvious that the capsule need not be placed adjacent to the electrode inasmuch. as the electrode serves as a means ,of heating the capsule when the capsule is placed in or adjacent thereto.

Having described my invention it is understood that various modifications may be made therein without deviating from the scope and it is specifically understood that the mvention is not limited .by the examples'described herein except'as limited in the accompanying claims.

What is claimed is:

1. A method of introducing materials within an evacuated envelope comprising sealing the material within a glass capsule, scratching the surface of the glass capsule, to provide capsule within the envelope, evacuating the envelope, and breaking the capsule at the weakened portion to release the material.

2. A method of introducing materials within an evacuated envelope comprising sealing the material within a glass capsule, scratching the surface of the glass capsule, to provide a weakened portion, inserting the capsule within the envelope, evacuating the envelope, and subjecting the capsule to heat which breaks it at the weakened portion and releases the material from the capsule into the. envelope.

3. A method of inserting a material within a sealed and evacuated positive column lighting tube envelope having electrodes comprising sealing the material within a glass capsule, scratching the glass wall of the capsule, inserting a capsule within the envelope in close proximity evacuating the envelope, subjecting the electrode to a high temperature which breaks the capsule while continuing the evacuation, charging the envelope with an inert gas, and sealing the envelope.

4. A to handle within an evacuated and sealed positive column lighting tube envelope having Wall of the electrode chamber of the envewhich a metal such as potassium is sealed, is l If other means a weakened portion, insert ng the to each electrode,

method of inserting a metal diflicult electrodes comprising sealing the metal within a glass capsule, scratching the capsule, inserting the capsule within the electrode, evacuating the envelope, driving ofl' occluded gases by passing an electrical current between the electrodes, passing a higher electrical current between the electrodes than utilized to drive ofi' occluded gases which heats the electrode and heats and breaks the capsule while evacuation continues, charging the envelope with at least oneilluminant material, and sealing the envelope.

5. A method of inserting a metal diflicult to handle within an evacuated and sealed positive column lighting tube envelope having electrodes with perforated walls comprising sealing the metal within a glass capsule, scratching the capsule, inserting the capsule within the electrode and anchoring it there in, evacuating the envelope, driving oif occluded gases by passing an electrical current between the electrodes, passing a higher elec- 4 trical current between the electrodes than utilized to drive off occluded gases which 'heats the electrode and heats and breaks the capsule whileevacuation continues, charging the envelope with at least one illuminant material, and sealing the envelope.

6. A method of inserting a metal diflicult to handle within an evacuated and sealed positive column lighting tube having high resistance electrodes comprising sealing the metal within a glass capsule, scratching the capsule, inserting the capsule within the electrode, evacuating the envelope, driving off occluded gases by passing an electrical current between the electrodes, heating the electrode to a higher temperature than utilized to drive ofi occluded gases by placing each electrode at the center of a high frequency field to'break the capsule while continuing evacuation of the envelope, charging the envelope with at least one illuminant material, and sealing the increased by the application envelope. 1

7 The method of making a luminous as discharge tube having a cathode treated wlth volatile thermo emissive material which comprises enclosing the said material in a frangible capsule weakened at one or more points by a scratch or scratches in the surface thereof so that the vapor pressure of the contents i of heat readily ruptures the weakened capsule and spatters the contents in the vicinity, positioni the capsule within the tube and in the vicimtyof. the cathode, evacuating and scavenging the tube and applying sufiicient heat to the capsule to create sufiicient pressure of the contents to burst the capsule weakened by the said scratches. V I a 8. A method of making a luminous as discharge tube having a cathode treated with a volatile thermo emissivematerial which comprises enclosing the said material in a frangible capsule having walls of substan- 

